Plankton structure a in shallow coastal zone at Admiralty Bay, King George Island West ­Antarctic Peninsula (WAP): composition of ­phytoplankton and influence of benthic ­diatoms

The phytoplankton composition and biomass are being monitored in Admiralty Bay, Antarctic Peninsula since 2002 to detect possible interannual changes on a long-term monitoring perspective. In this report, we present the results of the 2009/2010 monitoring program regarding the phytoplankton composition during the PROANTAR XVIII operation. The community was dominated by both planktonic and benthic diatoms. A total of 140 species were found, many of them awaiting further morphological studies to determine their specific identity. A preliminary assessment of habitat preferences was made, showing that the diatoms in the Admiralty Bay came from distinct substrates like ice, rocks, sediments, plankton and macroalgae. These results indicate that benthic microalgae, particularly diatoms, play an important role in primary productivity of the pelagic community in inshore waters. The next steps will be to refine identification to analyse the whole water samples and to relate the results with the environmental and hydrographical features in Admiralty Bay.